Multimedia broadcast multicast service (MBMS) frequency prioritization

ABSTRACT

An indicator indicates whether Multimedia Broadcast Multicast Service (MBMS) Service Area Identifier (SAI) frequency information broadcast from a wireless communication network to a wireless communication device is being updated dynamically. Based on the indicator, the wireless communication device may apply different procedures for acquiring an MBMS service.

RELATED APPLICATIONS

This application claims the benefit of priority of U.S. provisionalpatent application Ser. No. 61/611,893, entitled RESELECTION PRIORITYWITH MBMS ASSISTANCE INFORMATION, filed on Mar. 16, 2012, andincorporated in its entirety herein.

FIELD

This invention generally relates to wireless communications and moreparticularly to Multimedia Broadcast Multicast Service (MBMS) frequencyprioritization.

BACKGROUND

Multimedia Broadcast Multicast Service (MBMS) is a Point-to-Multipoint(PTM) interface specification designed to provide efficient delivery ofbroadcast and multicast services within 3rd Generation PartnershipProject (3GPP) cellular networks. Examples of MBMS interfacespecifications include those described in Universal MobileTelecommunications System (UMTS) and Long Term Evolution (LTE)communication specifications. For broadcast transmission across multiplecells, the specifications define transmission over single-frequencynetwork configurations. Intended applications include mobile TV, news,radio broadcasting, file delivery, emergency alerts, and others. Whenservices are broadcasted by MBMS, all cells inside an MBSFN (MultimediaBroadcast multicast service Single Frequency Network) area transmit thesame MBMS service. Services that can be provided using PTM can bereferred to as PTM compatible services. As discussed herein, MBMSservices and MBMS content are PTM compatible services that are providedvia MBMS.

Users access these services and obtain the MBMS content through wirelesscommunication devices such as cellular phones, tablets, laptops, andother devices with wireless transceivers that communicate with the basestations within the communication system. The base stations, sometimesreferred to as eNodeBs or eNBs, provide wireless services to thewireless communication devices, sometimes referred to as user equipment(UE) or UE devices, within cells.

A user can access at least some multimedia services through a UE usingeither a Point-to-Point (PTP) connection or a Point-to-Multipoint (PTM)transmission. PTP services are provided using Unicast techniques and PTPtransmissions are performed using MBMS communication in 3GPP systems.Accordingly, a PTM compatible service can be provided using eitherUnicast service or MBMS. In order to avoid inefficient use of resources,current specifications and proposals include provisions for tracking andevaluating the number of UEs that have been characterized by thenetwork, at least for resource management purposes, as UEs that willreceive the PTM compatible service. The network monitors the number ofUEs accessing an MBMS service, congestion levels and other communicationparameters, and makes appropriate adjustments to the network to maintainefficient use of communication resources. For example, resources aremore efficiently allocated by only providing a specific PTM compatibleservice with MBMS when the number of wireless communication devices inconnected mode (connected mode UEs) receiving the specific PTMcompatible service using PTM is sufficiently high. When there are manyusers that are using, or will likely use, a particular PTM compatibleservice in the MBSFN area, then the network allocates resources todeliver the program by MBMS via PTM. In other words, if there are manyusers that are interested in getting a particular PTM compatible serviceand, therefore, are operating a wireless communication device that isreceiving, or is likely to receive, the PTM compatible service in theMBSFN area, then the network allocates resources to deliver the specificPTM compatible service using PTM techniques. On the contrary, if thereare a small number of users that are interested in and will use theparticular PTM compatible service, it is more efficient to deliver thePTM compatible service using PTP techniques such as those used with aUnicast connection. When services are broadcasted by PTM using MBMS, allcells inside the MBSFN (Multimedia Broadcast multicast service SingleFrequency Network) area are required to broadcast the same informationso the amount of wasted resource could be very large when very fewwireless communication devices (UEs) are obtaining the service. Inaccordance with current specifications, therefore, a program or serviceis discontinued from PTM transmission when the size of the audienceusing wireless communication devices in connected mode decreases below athreshold. For activation of a service by PTM, the network evaluates thenumber of wireless communication devices which are PTM capable but whichare receiving a given PTM compatible service via PTP such as through aUnicast service as well as devices that have been identified as devicesthat will receive the PTM compatible service. The network characterizesdevices that are receiving the service or that are likely to receive theservice as devices that will receive the service for purposes ofresource management and determines the number of PTM capable wirelesscommunication devices (UEs) that are characterized as devices that willreceive the service. When that number of PTM capable wirelesscommunication devices (UEs) exceeds a threshold, the service is providedusing PTM.

In order for the network to receive reception status feedback from thewireless communication devices (UEs), the current 3GPP specificationsspecify Counting Procedures. A Counting Procedure is initiated by thenetwork. A Multi-cell/multicast Coordination Entity (MCE) in the networksends a request to each eNodeB providing the specific PTM compatibleservice in the MBSFN area to send a Counting Request to the wirelesscommunication devices (UEs). The Counting Request contains a list ofspecific PTM compatible service identifiers requiring wirelesscommunication device (UE) feedback. The connected mode wirelesscommunication devices (UEs) which are receiving, or interested inreceiving, the identified content respond with a Counting Responsemessage including the specific PTM compatible service identifiers thatare of interest.

The current communication specifications, therefore, provide for aCounting Procedure that allows for the network to determine a number ofwireless communication devices (UEs) in the connected mode that areinterested in specific MBMS content. Proposals have been offered forcounting wireless communication devices (UEs) in idle mode that arereceiving, or will likely receive, a specific PTM compatible service.

The network also monitors the number of wireless communication devices(UEs) that are accessing a particular frequency and performs loadbalancing procedures to avoid congestion. For example, when a thresholdpercentage of total capacity is reached, the network applies proceduresfor reducing the number of wireless communication devices on theparticular frequency.

Current 3GPP specifications specify a mechanism for providing MBMSfrequency information to the wireless communication devices, where theMBMS frequency information allows a wireless communication device todetermine the frequencies at which particular MBMS services areavailable. More specifically, the most 3GPP Revision 11 specificationprovides that base stations (eNBs) transmit MBMS Service AreaIdentification (SAI) frequency information using the System InformationBlock 15 (SIB15). The MBMS SAI frequency information providesinformation regarding the relationship between SAIs and frequencies. Forexample, the SAI frequency information includes the correlation betweenMBMS SAIs and frequency channels for all MBMS frequency channels for theserving base station (eNB) as well as for neighboring base stations(eNBs). The wireless communication also obtains a User ServiceDescription (USD) which provides information related to the relationshipbetween SAIs and MBMS services. For example the USD contains at leastTemporary Mobile Group Identities (TMGIs) and MBMS Service AreaIdentities (SAIs) as well as an association between the TMGIs and theMBMS SAIs. The wireless communication device downloads the USD and mayreceive the USD from a base station in some circumstances. The MBMSfrequency information which provides the relationship between MBMSservices and frequencies can be determined based on the USD and the SAIfrequency information.

Network changes result from the counting procedures, load balancing, andother network management may result in changes to the MBMS frequenciesand services such that the frequencies carrying a particular MBMSservice are changed. Accordingly, in some cases the network adjustmentsmay result in changes in the frequency information related to MBMSservices.

SUMMARY

An indicator indicates whether Multimedia Broadcast Multicast Service(MBMS) Service Area Identifier (SAI) frequency information broadcastfrom a wireless communication network to a wireless communication deviceis being updated dynamically. Based on the indicator, the wirelesscommunication device may apply different procedures for acquiring anMBMS service.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a communication system that is capable ofproviding Multimedia Broadcast Multicast Service (MBMS) to wirelesscommunication devices.

FIG. 2 is a block diagram of a base station (eNB) and wirelesscommunication device (UE) where the base station (eNB) transmits MBMSSAI frequency information and the indicator using the System InformationBlock 15 (SIB15).

FIG. 3 is flowchart of a method performed in a wireless communicationdevice (UE) such as the wireless communication device.

FIG. 4 is a flowchart of a first example of a method of an MBMSfrequency prioritization procedure for non-dynamically updated MBMSfrequency information.

FIG. 5 is a flowchart of a second example of a method of an MBMSfrequency prioritization procedure for non-dynamically updated MBMSfrequency information.

FIG. 6 is a flowchart of a third example of a method of an MBMSfrequency prioritization procedure for non-dynamically updated MBMSfrequency information.

FIG. 7 is a flowchart of a method performed in a MBMS communicationsystem such as the communication system.

DETAILED DESCRIPTION

As described above, current communication specifications and proposalsinclude techniques for providing MBMS frequency information to wirelesscommunication devices (UEs). In accordance with current communicationspecifications such as (3GPP TS 36.304 version 11.2.0) wirelesscommunication devices (UEs) prioritize MBMS frequencies based on thefrequency information. The frequency information, however, may changewhen adjustments to the network are made. Currently, the 3GPPspecification does not require that the frequency information bedynamically updated. In other words, there is no requirement for thebase stations (eNBs) to update the frequency information transmitted tothe wireless communication devices even if the data has changed. As aresult, it is possible that a wireless communication device willprioritize an MBMS frequency in situations where the MBMS service is nolonger available at that particular frequency.

In the embodiments discussed below, however, an indicator is transmittedto the wireless communication devices indicating whether the frequencyinformation is dynamically updated. For the examples, the indicator iseither a true indicator indicating the frequency information is updateddynamically or a false indicator indicating the frequency information isnot dynamically updated. A wireless communication device (UE) applies adynamic frequency prioritization procedure when a true indicator isreceived and applies a non-dynamic frequency prioritization when a falseindicator is received.

FIG. 1 is a block diagram of a communication system 100 that is capableof providing Multimedia Broadcast Multicast Service (MBMS) to wirelesscommunication devices 102, 104, 106. The communication system 100,therefore, is referred to as an MBMS communication system 100. Thevarious functions and operations of the blocks described with referenceto the MBMS communication system 100 may be implemented in any number ofdevices, circuits, or elements. Two or more of the functional blocks maybe integrated in a single device and the functions described asperformed in any single device may be implemented over several devices.For example, at least some of the functions of the MCE 114 may beperformed by the base stations 110-112 or other entities within the corenetwork 113. A cellular communication system is typically required toadhere to a communication standard or specification. TheThird-Generation Partnership Project Long-Term Evolution (3GPP LTE)communication specification is a specification for systems where basestations (eNodeBs) provide service to wireless communication devices(user equipment (UE) devices) using orthogonal frequency-divisionmultiplexing (OFDM) on the downlink and single-carrierfrequency-division multiple access (SC-FDMA) on the uplink. Although thetechniques described herein may be applied in other types ofcommunication systems, the exemplary systems discussed herein operate inaccordance with a 3GPP LTE communication specification. A communicationspecification may include several revisions as modifications are adoptedby the standard body. Although the examples discussed herein may be usedwith any number of revisions of the 3GPP LTE communicationspecification, the examples operate in accordance with modification ofthe Radio Resource Control (RRC) specification TS 36.331 version 11.2.0Release 11.

The MBMS communication system 100 is capable of transmitting certaincontent to wireless communication devices (UEs) using either Unicastservices or the MBMS services. The content, referred to herein as PTMcompatible service and MBMS service may be a service, data, or a programthat can be accessed through a wireless communication device. Examplesof PTM compatible services include streaming audio and video and othermultimedia data. Accordingly, as discussed herein, a PTM compatibleservice may be provided using PTP (Unicast) service or PTM service. Forthe examples, the PTM service is provided using MBMS and referred to asa MBMS service. The communication system 100 may also provide othercommunication services such as wireless telephone service, SMS, textmessaging, and other services.

The MBMS communication system 100 includes several base stations 110-112sometimes referred to as eNodeBs or eNBs (110-112), that communicatewith the wireless communication devices (UEs) 102, 104, 106 bytransmitting downlink signals and receiving uplink signals transmittedfrom the wireless communication devices 102, 104, 106. The wirelesscommunication devices (UEs) 102, 104, 106 are any wireless communicationdevices such as mobile phones, transceiver modems, personal digitalassistants (PDAs), and tablets, for example. The wireless communicationdevices may be referred to as cell phones, mobile devices, smart phones,and other names. In systems operating in accordance with 3rd GenerationPartnership Project (3GPP) communication standards, the wirelesscommunication devices 102, 104, 106 are often referred to as userequipment (UE), (UEs), or UE devices. Since for the examples providedherein the system operates in accordance with a 3GPP communicationspecification, the term eNodeB may be used to refer to the base stationsand the wireless communication devices may be referred to as UEs.

The base stations (eNodeBs) 110-112 are connected to a network through abackhaul in accordance with known techniques. The MBMS communicationsystem 100 provides PTM services by transmitting the PTM compatibleservice through multiple base stations (eNodeBs) 110-112 using PTM andMBMS techniques.

A Multi-cell/multicast Coordination Entity (MCE) 114 manages MBMScommunications by exchanging information and instructions with the basestations (eNodeBs) 110-112. The MCE 114 is typically a logical entitythat is implemented over several devices or network elements within thecore network 113. The MCE 114, however, may be implemented within asingle device or network element in some circumstances. The MCE 114performs functions such as admission control and allocation of radioresources for the MBMS Single Frequency Network (MBSFN) area 116 formulticell MBMS. The core network 113 also includes a Mobility ManagementEntity (MME) 115. The MME is a logical entity and the control node forthe LTE network. The MME 115 handles idle mode UE tracking and pagingprocedure including retransmissions. The MME is also involved in thebearer activation/deactivation process. In managing the MBMScommunications, the MCE 114 invokes counting procedures, acquirescounting results for one or more PTM compatible services, and monitorscapacity and congestion of communication resources. Based on thecounting procedure results, congestion evaluations, and possibly otherfactors, the MCE 114 determines in coordination with the eNB whether aPTM session should be suspended, established, and resumed. A MBMSsession is a session where a PTM compatible service is multicast fromthe eNodeBs 110-112. Other than the new procedures related to managingfrequency information and providing frequency information and dynamicfrequency information indicators described herein, the MCE 114 operatesin accordance with one or more current 3GPP specifications to performthese tasks for the examples described herein.

An MBMS Gateway (MBMS GW) 117 in the core network 113 is the entry pointof incoming broadcast/multicast traffic. The MBMS GW 117 broadcasts thepackets to all base stations (eNBs) within a service area and alsoperforms MBMS session management. The core network 113 may include anycombination of hardware and code for implementing the functionsdescribed here as well as the overall operation of the system 100.Accordingly, the core network 113 may include other entities andfunctional blocks not shown in FIG. 1.

Communication resources are divided at least by frequency such that eachof several downlink frequency channels 118 is independently assigned toan MBMS service or other communication service. In accordance withconventional techniques, the core network 113 determines whichfrequencies are to be used for transmitting the MBMS services. The corenetwork 113 assigns one or more frequency channels for transmission ofMBMS services that are to be provided by a base station. Theavailability of a particular MBMS service may differ between basestations depending on which frequencies are supported by each basestation. For example, frequencies F1 and F2 may be used by a first basestation 110, frequency F2 may be used by a second base station 111, andfrequency F3 may be used by a third base station 112 to provide the sameMBMS service or program.

MBMS frequency information 120 identifies the frequency channel(s) usedfor providing each MBMS service. Although, in some situations, thefrequency information 120 may be provided in a single transmission thatdirectly identifies the frequency channels and MBMS services, typically,the wireless communication device must apply stored program informationto received SAI frequency information to determine the MBMS service tofrequency relationship. In the TS 36.331 version 11.2.0 Release 11specification, MBMS SAI frequency information 121 provides therelationship between MBMS SAIs and frequency channels for all MBMSfrequency channels for the serving base station (eNB) as well as forfrequencies that are operated by either the serving base station or theneighboring base stations (eNBs). Accordingly the wireless communicationdevices (UEs) determine the MBMS frequency information 120 from the MBMSSAI frequency information 121.

Conventional techniques and communication specifications, however, donot apply or specify requirements regarding the age of the frequencyinformation data. As a result, the frequency information may beinaccurate due to network changes that are not reflected in the data.For example, if a particular MBMS service is no longer transmitted on afrequency in response to the latest counting procedure, transmittedfrequency information may still indicate that the MBMS service isavailable at the particular frequency when the MBMS SAI frequencyinformation 121 is not updated.

In accordance with embodiments of the invention, however, an indicator122 is transmitted to the wireless communication devices (UEs) 102, 104,106 indicating whether the MBMS SAI frequency information 121 isdynamically updated. For the examples herein, the indicator 122indicates one of two indications including a true indication indicatingthat the MBMS SAI frequency information 121 is updated dynamically and afalse indication indicating that the MBMS SAI frequency information 121is not dynamically updated. As discussed herein, the MBMS SAI frequencyinformation is considered to be dynamically updated if it is at leastupdated when there is a change in the frequency information. In somesituations, however, “dynamically updated” may be defined as an updatingrate above a threshold rate of updating. In other situations,“dynamically updated” may be defined as resetting the MBMS SAI frequencyinformation 121 after every network change, even if the MBMS SAIfrequency information 121 has not be changed since the last resetting.The indicator 122, therefore, also provides an indication of thereliability of the frequency information. A wireless communicationdevice (UE) can interpret the frequency as being more reliable when atrue indicator is received, for example. For the examples, the indicator122 is a single bit within the SIB15. Therefore, as compared to aconventional SIB15, the SIB15 of the examples includes an additionalreserved field for the indicator.

The 3GPP specifications require that the wireless communication devices(UEs) follow a strict frequency prioritization procedure. The corenetwork provides a network prioritization list that typically includes aprioritized list of up to eight frequencies. The wireless communicationdevices (UEs) acquire the frequencies in the ordered priority. Oneexception to applying the network prioritization list occurs when awireless communication device (UE) is accessing an MBMS service. Thewireless communication device (UE) prioritizes the MBMS servicefrequency to attempt to access the MBMS service. When the MBMS serviceis no longer desired, the wireless communication device (UE) returns tofollowing the network prioritization list.

FIG. 2 is a block diagram of a base station (eNB) and wirelesscommunication device (UE) where the base station (eNB) transmits MBMSSAI frequency information 121 and the indicator 122 in the SystemInformation Block 15 (SIB15) 200. The downloaded information of a UserService Description (USD) 202 and the MBMS SAI frequency information 121form the MBMS frequency information 120. Typically, the USD 202 is anapplication file that is downloaded by the wireless communicationdevices (UEs). In FIG. 2, the dashed line from the core network 113through the base station 110 indicates that the USD is downloaded over awireless link in some circumstances. The USD 202 contains at leastTemporary Mobile Group Identities (TMGIs) 206 and MBMS Service AreaIdentities (SAIs) 208 as well as an association between the TMGIs andthe MBMS SAIs. Each SAI uniquely identifies a Service Area (SA). An MBMSService area is defined as the area within which data of a specific MBMSsession are sent. Each individual MBMS session may be sent to adifferent MBMS Service Area. Each MBMS Service Area comprises of one ormore MBMS SAIs.

Each TMGI identifies an MBMS service. Therefore, the USD 202 providesinformation to the wireless communication devices regarding which MBMSSAI is providing each TMGI. A particular TMGI may be provided by morethan one MBMS SA. Accordingly, a TMGI may be associated with more thanone MBMS SAI. The USD also includes USD MBMS frequency information (notshown) indicating the association between frequency channels and MBMSSAIs. The USD MBMS frequency information in the USD, however, may not beaccurate since frequency channels are controlled by the particularnetwork and may change over time. MBMS SAI frequency information 121 isprovided by the base station by another transmission. In accordance with3GPP TS 36.331 version 11.2.0 Release 11, the MBMS SAI frequencyinformation 121 is transmitted in the System Information Block 15(SIB15) 200 and includes the correlation between MBMS SAIs and frequencychannels for all MBMS frequency channels for the serving base station(eNB) as well as for frequencies that is operated by either the servingbase station or the neighboring base stations (eNBs). For the examplesdiscussed herein, the SIB15 is formatted and transmitted in accordancewith the 3GPP TS 36.331 version 11.2.0 Release 11 except that anadditional field is assigned for the indicator 122. The indicator 122may be transmitted in other ways in some situations.

The wireless communication device (UE) 212 includes a receiver 214,transmitter 216 and a controller 218. The wireless communication device(UE) 212 of FIG. 2 is an example of the wireless communication devices102, 104, 106 of FIG. 1. The various functions and operations of theblocks described with reference to wireless communication device 212 maybe implemented in any number of devices, circuits, or elements. Two ormore of the functional blocks may be integrated in a single device andthe functions described as performed in any single device may beimplemented over several devices. For example, at some of the functionsof the controller 218 may be performed by the receiver 214 ortransmitter 216.

The receiver 214 receives downlink signals transmitted from the basestations in accordance with the 3GPP communication specification. Thetransmitter transmits uplink signals to the base stations in accordancewith the 3GPP communication specification. The controller 218 is anyprocessor, microprocessor, processor arrangement, or computer that canexecute code to perform the functions described herein and to facilitatethe overall operation of the wireless communication device 212. Thecontroller typically includes, or is connected to, a memory (not shown)which may be any combination of persistent and temporary memory suitableto store information, data and/or code. The SIB15 is transmitted overdownlink signals and processed by the receiver 214 and controller 218 toextract the information related to MBMS SAI frequency information 210and the indicator 122. In some cases, the USD 202 is downloaded throughthe base station 110 and received at the receiver 214 although the USD202 may be downloaded through other means, such as through a computerthat is connected to the core network 113. The controller 218 processesthe USD file to determine TMGI 206 and MBMS SAI 208. Accordingly, theMBMS frequency information 120 and the indicator 122 are received at thecontroller 218.

The controller 218 evaluates the indicator to determine whether the MBMSSAI frequency information 121 is dynamically updated. When there is needfor the wireless communication device to access a MBMS frequencychannel, the controller 218 performs the procedure for reselecting afrequency listed in the MBMS frequency information. For the examplesdiscussed herein, the controller either performs a reselection procedurefor dynamically updated information or a reselection procedure fornon-dynamically updated information. If the indicator 122 indicates thatthe MBMS SAI frequency information 121 is updated dynamically, thecontroller reselects the identified frequency and prioritizes thefrequency. More specifically, the controller performs the appropriatefunctions to tune the receiver to the particular MBMS frequency channeland decode the MCCH. The MCCH information is transmitted periodically,using a configurable repetition period. Scheduling information is notprovided for MCCH (i.e., both the time domain scheduling as well as thelower layer configuration are semi-statically configured in SystemInformation Block 13 or SIB13). The MCCH provides the MBMS controlinformation for the wireless communication device to determine ifservices it is interested to receive are ongoing. More specifically, theMCCH carries the MBSFNAreaConfiguration message, which indicates theMBMS sessions that are ongoing as well as the corresponding radioresource configuration. The MCCH may also carry the MBMSCountingRequestmessage, when the network is to count the number of UEs in RRC_CONNECTEDmode that are receiving or interested to receive one or more specificMBMS services. Change of MCCH information only occurs at specific radioframes (i.e., the concept of a modification period is used). Within amodification period, the same MCCH information may be transmitted anumber of times. When the network changes some of the MCCH information,it notifies the wireless communication devices about the change during afirst modification period. In the next modification period, the networktransmits the updated MCCH information.

Upon receiving a change notification, a wireless communication deviceinterested to receive MBMS services acquires the new MCCH informationimmediately from the start of the next modification period. Since theMCCH can only change at modification boundaries, the wirelesscommunication device does not need to monitor each MCCH transmission,but only at the boundary of the new modification period.

If the indicator indicates that the MBMS frequency information is notdynamically updated, the controller 218 invokes a non-dynamic frequencyreselection procedure. Depending on the particular implementation, thenon-dynamic frequency reselection procedure may require a predeterminedaction or may include a procedure for the controller to determine thepreferred action. For the examples discussed herein, the controllerattempts to access the MBMS frequency channel and if the MBMS service isavailable, accesses the MBMS service. In some situations the MCCH maynot include the information for accessing the MBMS service therebyindicating that the MBMS service is not currently available on theparticular MBMS frequency. Different actions can be taken based on theparticular implementation if the MBMS service is not available. For thethree examples discussed immediately below, the controller 218 tunes tothe MBMS frequency and attempts to acquire the MBMS service. Morespecifically, the controller performs the appropriate functions to tunethe receiver to the particular MBMS frequency channel and decodes theMCCH. If the MCCH indicates the desired MBMS service is available, thecontroller applies the timing information provided in the MCCH to accessthe MBMS service. If, however, the MCCH does not indicate the MBMSservice is available, the controller performs one of the followingexemplary procedures.

In a first example of a non-dynamic frequency reselection procedure, thecontroller controls the wireless communication device to remain on theMBMS frequency and attempt to access the MBMS service by periodicallydecoding the MCCH. This procedure differs from conventional techniquesin that the controller may invoke a lower frequency of MCCH decoding ascompared to conventional systems. Such a procedure leads to reducedpower consumption since the required power for decoding the MCCH is notinsignificant. As a result, the controller can utilize the indicator tomodify prioritization procedure even though the wireless communicationdevice “camps” on the MBMS frequency.

In a second example of a non-dynamic frequency reselection procedure,the controller executes a procedure to tune to the frequency channelprioritized by the core network. Accordingly, the wireless communicationdevice refrains from applying the exception for prioritizing the MBMSfrequency channel for the desired MBMS service and operates inaccordance with the core network prioritization list. In manycircumstances, the prioritized frequency channel is the originalfrequency channel in use before the attempt to acquire the desired MBMSservice. The reselection procedure is the same as the reselectionprocedure applied when the wireless communication device is no longerinterested in MBMS.

In some situations, the non-dynamic frequency reselection procedureincludes the controller dynamically determining the course of actionwhen it is determined that the MBMS service is not currently available.Any combination of data, parameters, information, and criteria can beapplied by the controller, within the bounds of the standardsrequirements, to determine an appropriate course of action for thewireless communication device. In a third example, the controllerdetermines whether the user is interested in a second MBMS service ifthe first MBMS service is not available. If there is interest in asecond MBMS service, the controller executes a procedure to acquire thesecond MBMS service. If there is no interest in another MBMS service andthe first MBMS service is not available, the controller applies the corenetwork prioritization as discussed in the second example.

In some situations, the controller may attempt to acquire the first MBMSservice after an elapsed time after applying the network prioritization.For example, the wireless communication device may return to theoriginal frequency if the MBMS service is not available, wait apredetermined time, and then again attempt to acquire the MBMS serviceby tuning the MBMS service frequency. In other examples, the controllermay attempt to access another MBMS frequency listed as carrying thefirst desired MBMS service.

FIG. 3 is flowchart of a method performed in a wireless communicationdevice (UE) such as the wireless communication device 212. For thisexample, the method begins with the wireless communication device 212 inthe idle mode. The method can be modified in order to be applied towireless communication devices in connected mode.

At step 302, MBMS SAI frequency information 121 is received at thewireless communication device. As discussed above, the MBMS SAIfrequency information 121 is the information indicating to the wirelesscommunication device the relationship between SAIs and frequencies. Thisinformation is used by the wireless communication device 212 todetermine the MBMS frequency information 120 which provides therelationship between MBMS services and the MBMS frequency channels (MBMSservice frequencies).

At step 304, the indicator 122 is received. For the example, theindicator 122 is transmitted in the SIB15 as a one-bit flag. A trueindicator indicates that the MBMS SAI frequency information isdynamically updated and a false indicator indicates that the MBMS SAIfrequency information is not dynamically updated. The indicator 122,therefore, indicates to the wireless communication devices (UEs) 102,204, 206 whether the MBMS SAI frequency information is being updatedafter every occurrence of a network change that results in a change inthe MBMS SAI frequency information.

At step 306, it is determined whether the MBMS frequency information isdynamically updated. The controller in the wireless communication devicedecodes the SIB15 and determines the value of the indicator 122. Basedon the indicator value, the controller determines whether the MBMSfrequency information is dynamically updated. If it is dynamicallyupdated, the method continues at step 308. Otherwise, the methodcontinues at step 310.

At step 308, a reselection procedure using the MBMS frequencyinformation is performed. Data obtained from the USD 202 provides therelationship between TMGI 206 and the MBMS SAIs 208 and the data in theMBMS SAI frequency information 210 of the SIB15 provides therelationship between the frequency channels and the MBMS SAIs. Bycombining the data from the USD and the SIB15, the wirelesscommunication device 212 determines the relationship between the MBMSservice (TMGI) and the frequency channels. The wireless communicationdevice tunes to the MBMS frequency channel identified by the MBMSfrequency information as carrying the desired MBMS service. The wirelesscommunication device decodes the MCCH and applies the MCCH informationto acquire the MBMS service.

At step 310, an MBMS frequency prioritization procedure fornon-dynamically updated MBMS frequency information is performed. Thisnon-dynamic frequency prioritization procedure may be a dynamicoperation where the wireless communication device evaluates informationand determines the appropriate course of action or it may be apredetermined operation required by the system without evaluation by thewireless communication device. Examples of methods of MBMS frequencyprioritization procedures for non-dynamically updated MBMS frequencyinformation are discussed below with reference to FIG. 4, FIG. 5, andFIG. 6.

FIG. 4 is a flowchart of a first example of a method of an MBMSfrequency prioritization procedure for non-dynamically updated MBMSfrequency information. Accordingly, the method discussed with referenceto FIG. 4 is a first example of a method of performing step 310 of FIG.3.

At step 402, the wireless communication device tunes to the MBMSfrequency identified by the MBMS frequency information as providing thedesired MBMS service. The controller applies the relationships betweenTMGI, MBMS SAIs, and frequency channels as provided by the USD and SIB15to identify the MBMS frequency. The receiver is tuned to the MBMSfrequency.

At step 404, the MCCH is decoded. In accordance with known techniques,the MCCH is received and decoded.

At step 406, it is determined whether the desired MBMS service isavailable at the MBMS frequency. The MCCH information is evaluated todetermine whether the MBMS service is available. If the MCCH providesthe subframe, timing, and other information for receiving the MBMSservice, the MBMS service is available and the method continues at step406. Otherwise, the MBMS service is not available and the methodproceeds to step 410.

At step 408, the desired MBMS frequency is received. At step 410, adelay is applied before the method returns to step 404 where the MCCH isdecoded again. In some cases, the delay can be omitted.

Therefore, in the first example, the wireless communication device campsat the MBMS frequency even though the MBMS service is not available. TheMBMS frequency is prioritized. The wireless communication device will nolonger prioritize the MBMS frequency when the user is no longerinterested in the MBMS service. The MCCH is repeatedly decoded at everynew modification period until the service becomes available or otheraction is required. The frequency of the decoding may be less than aconventional system since the indicator indicates that the MBMSfrequency information may not be reliable.

FIG. 5 is a flowchart of a second example of a method of an MBMSfrequency prioritization procedure for non-dynamically updated MBMSfrequency information. Accordingly, the method discussed with referenceto FIG. 5 is a second example of method of performing step 310 of FIG.3. Steps 402, 404, 406, and 408 are executed as discussed above withreference to FIG. 4.

For the method of FIG. 5, the wireless communication device does notremain at the MBMS frequency when the MBMS service is not available asdiscussed with reference to FIG. 4. If it is determined that the MBMSservice is not available at step 406, the method continues to step 502,wherein the wireless communication device tunes to the frequencydictated by the network prioritization. The frequency may be anotherMBMS frequency identified as providing the desired MBMS service, theoriginal frequency before the wireless communication device attemptedthe reselection, or another frequency determined by the frequencyreselection priority set forth by the network. The wirelesscommunication device tunes to a new frequency and no longer prioritizesthe MBMS service frequency if the MBMS service is not available at theMBMS service frequency.

FIG. 6 is a flowchart of a third example of a method of an MBMSfrequency prioritization procedure for non-dynamically updated MBMSfrequency information. Accordingly, the method discussed with referenceto FIG. 6 is a third example of method of performing step 310 of FIG. 3.Steps 402, 404, 406, 408, and 502 are executed as discussed above withreference to FIG. 4.

For the method of FIG. 6, the wireless communication device does notremain at the MBMS frequency when the MBMS service is not available inthe example discussed with reference to FIG. 5. For the example of FIG.6, however, the wireless communication device only tunes to thefrequency dictated by the network prioritization list if the first MBMSservice is not available and the user is not interested in any otherMBMS service. If it is determined that the first selected MBMS serviceis not available at step 406, the method continues to step 602, wherethe wireless communication device determines whether there is interestin a second MBMS service. If there is no interest in any other MBMSservice, the method continues at step 502 where the wirelesscommunication device applies the network prioritization. Otherwise, themethod continues to step 604 before proceeding to step 402. At step 604,the wireless communication device determines the MBMS service frequencyof the second MBMS service based on the MBMS SAI frequency information121.

FIG. 7 is a flowchart of a method performed in a MBMS communicationsystem such as the communication system 100. The method described withreference to FIG. 7 is an example of a technique for broadcasting anindicator indicating to wireless communication devices whether MBMSfrequency information provided by the system 100 is updated dynamically.

At step 702, it is determined whether the MBMS frequency information haschanged. The system determines whether the MBMS SAI frequencyinformation 121 listed in the most recent transmission is accurate or ifchanges within the system have resulted in a change of at least one MBMSfrequency. In other words, a change has been determined to have occurredif a frequency channel is newly associated with a MBMS SAI or if afrequency channel previously associated with a MBMS SAI is no longerassociated with the MBMS SAI. If a change has occurred, the methodcontinues at step 704. Otherwise, the method remains at step 702monitoring the MBMS frequency information for a change.

At step 704, it is determined whether the MBMS frequency informationshould be updated. In most situations, the system will determine toupdate the frequency information. If, however, circumstances dictatethat new frequency information cannot be broadcasted at the presenttime, the determination is that the frequency information is not to beupdated. If the frequency information is to be updated, the methodcontinues at step 706. Otherwise, the method proceeds to step 710.

At step 706, the updated frequency information 120 is broadcasted. Inthe examples discussed herein, the data in the MBMS SAI frequencyinformation 210 in the SIB15 is changed to reflect the currentrelationship between SAI and frequency channel.

At step 708, the indicator indicating that the MBMS frequencyinformation 121 is dynamically updated is broadcast. In the examplesherein, the one-bit indicator 122 in the SIB15 is set to “true.” Themethod then returns to step 702.

At step 710, the indicator indicating that the MBMS SAI frequencyinformation 121 is not dynamically updated is broadcast. In the examplesherein, the one-bit indicator 122 in the SIB15 is set to “false.” Themethod then returns to step 702.

FIG. 7 provides one example for setting and broadcasting the indicator122. In some situations, however, it is possible that the system 100 isrequired to broadcast the indicator but is not configured to dynamicallyupdate MBMS SAI frequency information. In such situations, the basestation may permanently set the indicator 122 to false and not executethe procedure discussed with reference to FIG. 7.

Clearly, other embodiments and modifications of this invention willoccur readily to those of ordinary skill in the art in view of theseteachings. The above description is illustrative and not restrictive.This invention is to be limited only by the following claims, whichinclude all such embodiments and modifications when viewed inconjunction with the above specification and accompanying drawings. Thescope of the invention should, therefore, be determined not withreference to the above description, but instead should be determinedwith reference to the appended claims along with their full scope ofequivalents.

What is claimed is:
 1. A method in a Multimedia Broadcast MulticastService (MBMS) system comprising a plurality of base stations, themethod comprising: broadcasting from a base station to a wirelesscommunication device, MBMS Service Area Identifier (SAI) frequencyinformation providing a relationship between MBMS SAIs and servicefrequencies; and broadcasting an indicator indicating to the wirelesscommunication device whether the MBMS frequency information is beingdynamically updated, wherein broadcasting the indicator comprisesbroadcasting a one-bit flag in the System Information Block Type 15(SIB15) where the one-bit flag indicates one of two values comprising: atrue indicator indicating that the MBMS SAI frequency information isdynamically updated; and a false indicator indicating that the MBMS SAIfrequency information is not dynamically updated.
 2. The method of claim1, wherein the MBMS system is a 3rd Generation Partnership Project(3GPP) cellular network operating in accordance with a Long TermEvolution (LTE) communication specification.
 3. The method of claim 2,wherein the MBMS system operates in accordance with a Radio ResourceControl (RRC) specification having a revision no earlier than RRC TS36.331 version 11.2.0.
 4. The method of claim 1, wherein the MBMS SAIfrequency information comprises all MBMS service frequencies for thebase station and all MBMS service frequencies for neighboring basestations.
 5. The method of claim 1, wherein the indicator indicateswhether the MBMS SAI frequency information is updated after occurrencesof network changes resulting in a change to the MBMS frequencyinformation.
 6. The method of claim 5, wherein the occurrences ofnetwork changes comprise a change to at least one service frequency forat least one MBMS service in response to a counting procedure.
 7. Themethod of claim 5, wherein the occurrences of network changes comprise achange to at least one service frequency for at least one MBMS servicein response to adjustments to reduce network congestion.
 8. The methodof claim 5, wherein the occurrences of network changes comprise a changeto at least one service frequency for at least one MBMS service inresponse to load balancing.
 9. The method of claim 1, wherein thebroadcasting the MBMS SAI frequency information comprises: broadcastingthe MBMS SAI frequency information in a System Information Block Type 15(SIB15).
 10. A method in a wireless communication device operating in aMultimedia Broadcast Multicast Service (MBMS) system comprising aplurality of base stations, the method comprising: receiving, at thewireless communication device, MBMS Service Area Identifier (SAI)frequency information providing a relationship between MBMS SATs andservice frequencies; receiving an indicator indicating to the wirelesscommunication device whether the MBMS SAI frequency information is beingdynamically updated, wherein receiving the indicator comprises receivinga one-bit flag in a System Information Block Type 15 (SIB15) where theone-bit flag indicates one of two values comprising: a true indicatorindicating that the MBMS SAI frequency information is dynamicallyupdated; and a false indicator indicating that the MBMS SAI frequencyinformation is not dynamically updated.
 11. The method of claim 10,wherein the indicator indicates whether the MBMS SAI frequencyinformation is updated after occurrences of network changes resulting ina change to the MBMS SAI frequency information.
 12. The method of claim10, further comprising: determining MBMS frequency informationcorrelating a desired MBMS service to at least one frequency.
 13. Themethod of claim 12, wherein the determining the MBMS frequencyinformation comprises evaluating User Service Description (USD)information and the MBMS SAI frequency information.
 14. The method ofclaim 13, wherein the USD information comprises MBMS Service AreaIdentifiers (SAIs) and MBMS Temporary Mobile Group Identities (TMGIs)and association between at least TMGI and each of at least some of theMBMS SAIs.
 15. The method of claim 10, further comprising: in responseto receiving the true indicator, tuning to an identified MBMS servicefrequency identified by the MBMS frequency information as carrying thedesired MBMS service, the tuning without decoding a Multicast ControlChannel (MCCH) of an MBMS service frequency other than the identifiedMBMS service frequency.
 16. The method of claim 15, further comprising:in response to receiving the false indicator, tuning to the identifiedMBMS service frequency identified by the MBMS frequency information asproviding the desired MBMS service; and remaining on the identified MBMSservice frequency if the desired MBMS service is not available at theidentified MBMS service frequency.
 17. The method of claim 15, furthercomprising: in response to receiving the false indicator, tuning to theidentified MBMS service frequency identified by the MBMS frequencyinformation as providing the desired MBMS service; and tuning to anotherfrequency in accordance with a network prioritization if the desiredMBMS service is not available at the identified MBMS service frequency.18. The method of claim 15, further comprising: in response to receivingthe false indicator, tuning to the identified MBMS service frequencyidentified by the MBMS frequency information as providing the desiredMBMS service; tuning to another identified MBMS service frequencyidentified for another MBMS service if there is interest in the anotherMBMS service and the desired MBMS service is not available at theidentified MBMS service frequency; and tuning to another frequency inaccordance with a network prioritization if the desired MBMS service isnot available at the identified MBMS service frequency and there is nointerest in another MBMS service.